1. Field of the Invention
The present invention relates to an optical transmission hinge apparatus for use in a foldable portable device such as a foldable mobile phone, a laptop computer, for effecting data communication by transmission/reception of light between two casings configured to be pivotable relative to each other about at least one hinge.
2. Description of the Related Art
Japanese Patent Application “Kokai” No. 2007-274057 discloses a portable wireless terminal device comprising a biaxial hinge arrangement which allow two casings respectively having a display section and a control section to be pivotally foldable about an opening/closing axis and which also allow the two casings to be pivotable also about a vertical pivot axis extending normal to the opening/closing axis. In this terminal device, optical communication devices are provided respectively in the two casings, i.e. the display section side casing and the control section side casing, to enable optical communication even when the two casings are displaced relative to each other. Further, optical path space is formed along the opening/closing axis and the vertical pivot center axis and a mirror is provided at the intersection point between the opening/closing axis and the vertical pivot center axis.
With the above-described art, light irradiated from one optical communication device travels through the space acting as the optical path and then is reflected by the mirror disposed at the intersection between the opening/closing axis and the vertical pivot center axis and enters the other optical communication device. In this construction, the relative positional relationship between the mirror and the optical communication devices is very important, so high precision is required for the assembly.
Further, as space is needed as an optical path, there is the risk of this optical path being easily blocked by an inadvertent movement of an adjacent disposed electric cable, entrance of dust, etc., thus hindering the communication. Moreover, if there occurs deformation in the casing(s), this deformation directly results in deformation of the optical path. So, the space acting as an optical path needs to have some “margin” to allow for such deformation. This requirement would make it difficult to form the casing(s) compact.
In view of the above-described state of the art, the primary object of the present invention is to provide an optical transmission hinge apparatus capable of maintaining optical communication even when its casings are pivotally moved relative to each other.